Get rid of the unused native code StringAddStub.

src/arm/code-stubs-arm.h

Index: src/arm/code-stubs-arm.h
diff --git a/src/arm/code-stubs-arm.h b/src/arm/code-stubs-arm.h
index 9b21d6f667652db523646217d6b7b734a9f73086..7a371f169490954dea366b6cde955d4936174989 100644
--- a/src/arm/code-stubs-arm.h
+++ b/src/arm/code-stubs-arm.h
@@ -57,18 +57,6 @@ class StoreBufferOverflowStub: public PlatformCodeStub {
 
 class StringHelper : public AllStatic {
  public:
-  // Generate code for copying characters using a simple loop. This should only
-  // be used in places where the number of characters is small and the
-  // additional setup and checking in GenerateCopyCharactersLong adds too much
-  // overhead. Copying of overlapping regions is not supported.
-  // Dest register ends at the position after the last character written.
-  static void GenerateCopyCharacters(MacroAssembler* masm,
-                                     Register dest,
-                                     Register src,
-                                     Register count,
-                                     Register scratch,
-                                     bool ascii);
-
   // Generate code for copying a large number of characters. This function
   // is allowed to spend extra time setting up conditions to make copying
   // faster. Copying of overlapping regions is not supported.
@@ -84,23 +72,6 @@ class StringHelper : public AllStatic {
                                          int flags);
 
 
-  // Probe the string table for a two character string. If the string is
-  // not found by probing a jump to the label not_found is performed. This jump
-  // does not guarantee that the string is not in the string table. If the
-  // string is found the code falls through with the string in register r0.
-  // Contents of both c1 and c2 registers are modified. At the exit c1 is
-  // guaranteed to contain halfword with low and high bytes equal to
-  // initial contents of c1 and c2 respectively.
-  static void GenerateTwoCharacterStringTableProbe(MacroAssembler* masm,
-                                                   Register c1,
-                                                   Register c2,
-                                                   Register scratch1,
-                                                   Register scratch2,
-                                                   Register scratch3,
-                                                   Register scratch4,
-                                                   Register scratch5,
-                                                   Label* not_found);
-
   // Generate string hash.
   static void GenerateHashInit(MacroAssembler* masm,
                                Register hash,
@@ -118,32 +89,6 @@ class StringHelper : public AllStatic {
 };
 
 
-class StringAddStub: public PlatformCodeStub {
- public:
-  explicit StringAddStub(StringAddFlags flags) : flags_(flags) {}
-
- private:
-  Major MajorKey() { return StringAdd; }
-  int MinorKey() { return flags_; }
-
-  void Generate(MacroAssembler* masm);
-
-  void GenerateConvertArgument(MacroAssembler* masm,
-                               int stack_offset,
-                               Register arg,
-                               Register scratch1,
-                               Register scratch2,
-                               Register scratch3,
-                               Register scratch4,
-                               Label* slow);
-
-  void GenerateRegisterArgsPush(MacroAssembler* masm);
-  void GenerateRegisterArgsPop(MacroAssembler* masm);
-
-  const StringAddFlags flags_;
-};
-
-
 class SubStringStub: public PlatformCodeStub {
  public:
   SubStringStub() {}